The conserved regions of sequence homology demonstrated between the papilloma-viruses will be further delineated. Viral DNA probes will be used in hybridization reactions with restricted immobilized heterologous papillomavirus DNA fragments 25 to 50 degrees C below the melting temperature of the DNAs to more precisely loalize regions of sequence homology. DNA from human tumors immobilized on nitrocellulose membranes will be examined for papillomavirus sequences by hybridization to virus DNAs and restriction fragments containing regions of sequence homology under nonstringent reannealing conditions. Antisera will be raised against the genus-specific cross-reactive papillomavirus structural polypeptide antigens and the virus-specific surface membrane tumor antigens on bovine papillomavirus-transformed cells. These antisera will be characterized as to their specificity using radioimmunoprecipitation. Formalin-fixed and frozen human tumors will be examined by indirect immunofluorescence and peroxidase-antiperoxidase tests for the presence of cross-reactive structural antigens or nonstructural virus-specific tumor antigens.